E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
{See also Earthstars Table.} "For purposes of field identification, G. fimbriatum might be regarded as an example of G. saccatum, without a line delimiting the mouth of the spore sac. There are other characters, such as the smaller spores which distinguish it." (Smith(49), Latin names italicized). Features include 5-9 non-hygroscopic rays, stemless or very short-stalked spore case, fibrillose peristome (mouth), comparative pale spore mass with pale capillitial hyphae, and small finely verruculose spores (Pegler(4)).

A collection from BC by A. McKinnon was deposited at the University of British Columbia and determined by P. Kroeger. Another BC collection at the University of British Columbia was collected by R. Winder and O. Ceska and determined by O. Ceska. Schalkwijk-Barendsen(1) lists the species for AB.

Outer Surface:
developing underground, more or less spherical to ovate, sometimes slightly umbonate, encrusted with debris; 2.1-5.8cm across when expanded, splitting about halfway into 5-9 non-hygroscopic rays, "rays arched and commonly recurved under the fruitbody"; outermost mycelial layer of rays "persistent or peeling off, encrusting soil and debris", middle fibrous layer of rays exposed when old "or by separation of mycelial layer when dry, rather papery, whitish to cream", innermost pseudoparenchymatous layer "whitish at first, becoming pale brown or yellowish brown", darker when old, "often splitting or partly peeling off", (Pegler), 0.8-2cm across before opening, the outer mycelial layer pallid to buff, forming a thin fibrillose coating, "outer wall splitting into 5 to 8(12) rays which have acute tips, sinuses extending down for about half the diameter of the fructification leaving the spores sac nestled in a bowllike base, the rays finally recurved back to almost touching the exterior of the bowl"; "mycelial layer tending to peel or flake off leaving the smooth pallid fibrous layer exposed"; fleshy layer much as in Geastrum saccatum, "when dried a thin, tan to dull brown coating over bowl, tending to become rimose at juncture with rays and on their surfaces", (Smith(49))

Inner layer:
spore case 0.9-2.5cm across, more or less spherical or depressed, pale gray-brown or buff, minutely puberulent with protruding, colorless or pale yellowish hairs; peristome [mouth] fibrillose, not distinctly delimited, (Pegler), spore case spherical with a conic mouth 0.8-1.5cm in diameter, unpolished, tan to dark brown; mouth fibrillose, not distinctly marked off from the rest of the spore case "but in some with a slightly different color or sheen", (Smith(49)), the mouth area may sometimes be paler, but there is no structural boundary, (Coker)

Spore Mass:
pale brown to brown when mature; columella "narrowly clavate, whitish", (Pegler), fuscous brown (Smith(49))

Stem:
spore case sessile [without a stalk] or with a very short stalk, (Pegler)

Microscopic:
spores 3-3.7 microns in diameter excluding ornamentation, 3.3-4 microns including ornamentation, round, "yellow-brown, finely verruculose", verruculae 0.1-0.3 microns high, about 0.2-0.5 microns wide, fine, isolated; basidia not seen; capillitial hyphae 2.5-7 microns wide, walls thickened, pale yellowish to almost colorless, finely tapered to the tips, "smooth or finely encrusted, especially towards the tips"; spore case with hairs that are hyphae 30-160 x 10-20 microns, cylindric-clavate, hyaline or pale yellowish, with thickened, refractive walls, (Pegler), spores 3-3.5 microns in diameter, round, with a very thin colorless envelope and minute projections extending into it, dark brown; capillitial threads 4-7 microns wide, nearly colorless (both in KOH and in iodine), very thick-walled, unbranched; forma pallidum has colorless spores and capillitium, (Smith(49))